National 5 Physics- POM

What are 3 states of matter?

• Solid - Liquid - (and) gas

Provide a diagram of changing state.

What is sublimation?

Sublimation is between gases and liquids.

Describe states of matter.

• (can break apart from the structure) (high energy) - (low energy)

Describe changes of state.

• Substances can change state- for example, solid ice can melt to become liquid water. - Changes of state involve latent heat energy/whenever a substance changes state latent heat energy is required.

What does latent mean?

Hidden.

What is latent heat?

The term used to describe the energy that causes a change of state without a change of temperature.

Does a state change have a change in temperature?

There is no change in temperature during a change in state.

What is specific latent heat?

The quantity of energy needed to change the state of 1kg of a substance.

What happens when solids melt or liquids boil?

Energy needs to be put in.

What happens when gases condense or liquids freeze?

Energy is given out.

What are the types of specific latent heat?

• Specific latent (heat) of fusion (solid

Describe water at 0 degrees celcius.

• Water freezes at 0 degrees celcius - (and) ice melts at 0 degrees celcius - ---> state change/no temperature change

Describe water at 100 degrees celcius.

A mixture of solid and liquid at 100 degrees celcius (this occurs with water and water vapour).

Describe the amount of energy involved in state changes of ice and water.

The amount of heat energy required to change 1kg of ice into water (or water into ice) is NOT the same as the energy required to change 1kg of water into steam (or steam into water).

Describe specific latent (heat) of fusion (in relation to ice and water- the value is given in scientific notation on the data sheet).

• It takes 334,000J of heat energy to turn 1kg of ice at 0 degrees celcius into liquid water at 0 degrees celcius. - This is the specific latent (heat) of fusion. - This applies to solid ---> and liquid ---> solid changes.

What is temp?

Temperature.

Describe specific latent (heat) of vaporisation (in relation to water and steam- the value is given in scientific notation on the data sheet).

• It takes 2,260,000J of heat energy to turn 1kg of water at 100 degrees celcius into steam at 100 degrees celcius. - This is the specific latent (heat) of vaporisaton. - This applies to liquid ---> gas and gas ---> liquid changes.

Describe the graph of change in temperature against time.

• The graph of the change in temperature against time is made up of slopes and horizontal lines - The slopes show where the temperature is changing: Eh= cm delta T - The horizontal lines show where the state is changing: Eh= ml

Where is the specific latent heat of fusion of materials and specific latent heat of vaporisation of materials found?

On the data sheet.

What do temperature values in latent heat questions show?

No change/a change in temperature.

Describe removing a block of ice from a freezer at -15 degrees celcius and heating it (in relation to formulas).

• To begin with, the solid ice will warm up: Eh= cm deltaT - When it reaches 0 degrees celcius: Eh= ml (fusion) - The liquid water will then heat up until it reaches 100 degrees celcius: Eh= cm deltaT - The water will turn in to steam at 100 degrees celciuis: Eh= ml (vaporisation)

Draw a heating curve, label it and describe it.

At the melting points and boiling points there is no increase in temperature as the substance has changed stated. Boiling point (vaporisation), melting point (fusion).

Draw and describe a cooling curve.

At the melting point and boiling point there is the increase in temperature until all (of the) substance has changed state.

What is there at the melting and boiling point?

There is no increase in temperature until all of the substance has changed state.

Describe the specific heat capacity, (for different states of the same substance).

It will be different.

What does f mean?

Fusion.

What is v?

Vaporisation.

Describe the latent heat of fusion and vaporisation.

• Latent heat of fusion: solid

What may you need to do if state and temperature changes are involved?

Use Eh= cm deltaT and Eh= ml (possibly multiple times).

Define pressure.

Pressure is defined as the force per unit area.

Describe pressure using a real life example.

• If someone stands on your foot wearing wellingtons, its not too bad. - If they are wearing a stiletto heel, they may make a hole in your foot. - Although the force applied is the same, the area is different. - We measure this effect using the idea of pressure.

What is 1Pa (Pascal) equivalent to?

1 Nm^-2 (1 Newton per square meter).

What is weight?

The force of a mass due to gravity.

Draw a block with a force going down.

Display w=mg in units.

W= mg N= Kg x N/Kg

Which unit is w=mg in?

The Dynamics (and space) unit.

How may you do multi-step calculations for pressure?

You might have to calculate area and/or force first.

What are v and f used to do?

These are subscripts of fusion and vaporisation.

What are gases made up of?

Tiny particles- atoms or molecules- that are widely separated and moving at speed.

What do the Gas Laws look at?

The relationships between three aspects of gases: - pressure - volume - (and) temperature

What is the volume of a gas?

The volume of the container it is in.

Describe the connection between volume and mass of a gas. Must they be the same?

No. Two bottles can contain the same mass of gas- but they have different volumes.

What is pressure of a gas caused by?

• The pressure of a gas is caused by the moving particles hitting against the sides of the container. - This applies a force over the area of the container- so we have a pressure (pressure is measured in pascals (Pa).

How do you alter the pressure (of a gas)?

• To alter the pressure you change change the size of a container ---> - The bigger the container, the lower the pressure

Draw and label a colder vs hotter gas.

Draw 2 volumes of gasses.

Draw gas pressure.

Describe the temperature of a gas.

• The temperature of a gas is a measure of the average speed of particles. - The faster the particles are moving, the higher the temperature of the gas

Describe heating a substance, increasing pressure.

• If you heat a substance you increase the energy increasing the pressure - You can add more particles increasing (pressure)

What are the constants of Boyles law?

• Temperature - Mass

What is the aim of the Boyle's law experiment?

To find a relationship between pressure and volume for a fixed volume of gas at a constant temperature.

What is the procedure of the Boyle's law experiment?

• The pump is used to increase the pressure (measured on the Bourdon gauge). - The oil moves up the tube, compressing the gas into a smaller volume (measured on the scale). - The pressure is then gradually reduced in steps, taking measurements of the volume each time.

Draw and label the Boyle's law experiment.

Provide an example of a results table for the Boyles law experiment.

Headings: Pressure (kPa), volume (cm^3), pxV and 1/V, a note is: the decrease maybe getting smaller

What do you notice about the value of pxV (Boyle's law)

The values of pxV are roughtly constant.

Draw a graph of p against V, and describe it. (Boyle's law)

Inversely proportional (disliked by scientists).

Draw a graph of p against 1/V and describe it (Boyle's law).

Directly proportional.

Provide a conclusion about Boyle's law (related to a graph of p against 1/V and 1/V) and label it.

y= mx + c (p= 1/2 + 0) P is proportional to 1/V p= k1/V pV= k

Describe p1V1=p2V2.

• For a sample of gas, the value of p x V is always the same. This means that we can write: p1V1 = p2V2 (the 1s and 2s are subscripts) - The "1" values are before, you change the gas. The "2" values are afterwards. - The p don't really matter but the 1s and 2s are subscripts, not superscripts eg. p to the power of 1 V to the power of 1 = p to the power of 2 V to the power of 2 give s you 0 marks for the whole question. - p1V1 = p2V2 may be okay if numbers (1s and 2s) aren't too big but its still wrong

What is the pressure temperature law also known as?

Gay-Lussac(s) Law.

What is kept constant for Gay-Lussac(s) law experiment?

• Mass - Volume

What is the object of the Gay-Lussac(s) (experiment)?

To find a relationship between pressure and temperature for a fixed mass of gas at a constant volume.

What is the procedure of the Gay-Lussac(s) law experiment?

• In the apparatus the water is heated - This heated the gas in the flask - Pressure readings on the Bourdon gauge are recorded at different temperatures as measured by the thermometer.

Provide a diagram of the Gay Lussac's law (experiment).

Provide an example of a results table (with results) with headings of Temperature (in degrees celcius) and pressure.

Draw a graph of p against t (in degrees celciuis).

What can you write if you measure temperature in kelvin (Charles law)?

V is proportional to T V= kT (k is a constant) V/T= k provided p is constant and a fixed mass of gas We usually write this as: V1/T1 = V2/T2 provided T is measured in Kelvin

Where can you find the specific capacity of materials?

On the data sheet.

Describe 1kg blocks.

• If you put a 1kg block of metal under the hot sun, it will heat up very quickly. - If you put a 1kg block of stone in the sun, it will take longer to warm up. - This is because different materials need different quantities of heat to raise their temperature.

What can you use heat energy (specific heat capacity) to calculate?

• To calculate the final temperature - To calculate use it with temperature rise - You can use it with other formulas

What is specific heat capacity?

• The specific heat capacity of a substance is the amount of (heat) energy needed to change the temperature of 1kg of a substance by 1 degree celcius. - Each substance has a different value of specific heat capacity.

Why was our value higher than the stated value for the specific heat capacity of aluminium in the experiment?

Because heat energy was lost to heating the surroundings.

Draw a labelled diagram of an experiment to measure specific heat capacity of aluminium.

What is the principle of energy conversion?

• Energy cannot be created or destroyed - It is always converted

Which calculations do you need to conduct (from the measurements taken) to find the specific heat capacity?

You need to calculate the: - Power of heater (using P= IV - Energy supplied to (the) block (using E= P x t) - Temperature rise of (the) block (deltaT) - Specific heat capacity using: c = E/m deltaT)

Which measurement's (from the experiment) do you need to take (to find the specific heat capacity)?

Measurement's of the: - Initial temperature of the block - Current supplied to the heater - Time heater is on - Final temperature of the block - Voltage across heater - mass of block

Describe the conservation of energy and heat transfer in relation to the experiment to find the specific heat capacity of aluminium.

• This applies to all types of energy, including heat energy. - In fact, we used this idea in the experiment to find the specific heat capacity of aluminium. - We used P= I x V and E= P x t to work out the total amount of electrical energy - We assumed that all of this energy was then converted into heat energy to warm up the block.

What are the steps of finding the specific heat capacity (using the experiment)?

• Set up the experiment - Complete these measurements as you do the experiment - Use your measurements to make these calculations

Draw a graph of P against T in Kelvin (with labels and celcius too).

Describe a graph of P against T (in degrees celcius) and Kelvin.

• The graph of P against T (in degrees celcius) is a straight line but it does not go through the origin. -If we draw the line "backwards" until it meets the temperature axis, it cuts it at -273 degrees celcius. - If we start our temperature scale at -273 degrees celcius and call it Zero Kelvin- we have a straight line through the origin.

If we measure temperature in Kelvin, how can we write Gay-Lussacs law?

p is proportional to T p= kT k is a constant p/T= k provided V is constant and a fixed mass of gas We usually write this as: P1/T1 = P2/T2 provided T is measured in Kelvin

What is Charles' Law?

The link between volume and temperature.

What are the constants of Charles law?

• Mass - Pressure

What is the object of the Charles law experiment?

To find a relationship between volume and temperature for a fixed mass of gas at constant pressure.

What is the procedure of the Charles law (experiment)?

• In the apparatus the temperature of the water is increased, as measured on the thermometer - When heated, the gas expands and pushes the mercury plug up the tube. - The linear scale gives a measure of the volume of the trapped gas.

Draw and label (an experiment of) Charle's law.

Provide a table that is filled in with headings of temperature (in degrees celcius) and volume (in cm^3).

Draw a graph of V against T in degrees celcius.

Draw a graph of V against T in kelvin degrees celcius.

Draw an example of Charles law.

What is Boyle's law?

P and V with T constant.

Describe a graph of V against T (in degrees c) and kelvin.

• The graph of V against T (in degrees celcius) is a straight line but it does not go through the origin - If we draw the line "backwards" until it meets the temperature axis, it cuts a minus 273 degrees celcius. - If we start our temperature scale at -273 degrees celcius and call it zero Kelvin- we have a straight line that cuts through the origin

How do you convert degrees celcius into kelvin?

Add 273.

How do you convert kelvin to degrees celcius?

Subtract 273.

Do you need to change units for gas laws?

The only unit to change is temperature into Kelvin.

Does Kelvin have a degrees symbol?

No.

For gas laws what is the required unit of temperature?

Kelvin (if you are given a temperature in Celcius- convert it to Kelvin, always convert to Kelvin)

What does "absolute zero" actually mean?

• At 0 Kelvin, the pressure of a gas is 0 - Pressure is cause by particles moving and hitting into the sides of the container - If the pressure is zero, this means the particles must have stopped moving - Because the particles can't move any less than "not moving" zero Kelvin (or minus 273 degrees celcius) is the lowest possible temperature - This doesn't mean its just the lowest temperature we can get down to- it is the lowest temperature there can be. - The average kinetic energy is 0.

Describe temperature.

• The water in the kettle is at a high temperature. - The temperature of the coffee is 85 degrees celcius - The temperature tells us how hot a substance is - It is a measure of the average kinetic energy of the particles in the substance - Temperature is measured in degrees celcius- Kelvin for gas laws, a jump of 1 kelvin= a jump of 1 degree celcius